Great assistance has been obtained from the use of dock levelers in unloading goods from trailer trucks at, for example, warehouses. The reason for this is that both the levels of the truck trailer beds, and the unloading ramps of the destination facilities vary, relative to ground level, with the result that where a platform is provided onto which goods in a trailer are to be unloaded, a ramp must be provided to bridge the trailer bed and warehouse platform to permit for example, electric trucks and dollies to ride from one to the other while transfering the load.
An example of a dock leveler is that disclosed in Rite Hite Corporation's Bulletin Number 8467-2 entitled "SEMI-AUTOMATIC HINGED LIP ADJUSTABLE DOCK LEVELER", wherein the leveler disclosed is what is known as a biased down dock leveler and is semi-automatic, meaning that when the vehicle leaves the warehouse dropping the ramp, the ramp first falls, retracting the lip. The ramp then rises to a position above the dock level and then automatically returns to the dock level, returning the lip to the keepers.
Such dock leveling system provides a hole, adjacent the outer end of the dock leveler near the lip for manually lifting the leveler by grasping the ramp. The leveler itself is spring counterbalanced, and therefore, when the leveler is lifted, the dock rises forcing the hinged lip upwardly and outwardly until it locks into place. While the spring counter-balancing, properly adjusted, reduces the stress on the person lifting the ramp, nevertheless, injuries to the arms, shoulders and back are common, resulting in considerable loss of time on the job, and union labour disputes. While hydraulic systems have been provided in the past, to assist in raising and lowering the ramp, they are both costly and when they break down, the ramp itself is inoperable until such system is repaired.
Furthermore, such hydraulic systems must be incorporated into such dock levelers at the time of installations with the result that a person wishing to modify his previously installed dock leveler to incorporate a hydraulic lift system, must replace the whole structure, thereby significantly increasing costs.
It is therefore, an object of this invention to provide an electrical elevating assembly, which can be added to existing biased down dock levelers of which can be incorporated at the time of installation of such levelers for lifting the leveler.
It is a further object of this invention to provide such an assembly at minimum cost and with few components requiring little maintenance.
It is a further object of this invention to provide an assembly which if it breaks down, does not render the dock leveler inoperable until the assembly is repaired.
Further and other objects of this invention will be realized by those skilled in the art, from the following summary of the invention and detailed description of the following preferred embodiment thereof.